I. Field of the Invention
The present invention relates generally to a bulk density sampling apparatus for continuously and repetitively measuring liquid samples from a bulk source and storing them for subsequent testing. More particularly, the present invention relates to a digitized, electronic liquid sampler that adaptively compensates and corrects for sampling errors.
II. Description of the Prior Art
Sampling devices have long been used under a variety of circumstances for collecting sample materials of both free flowing solids and fluids from various sources. For example, samples are routinely collected from waste water flow lines or reservoirs for subsequent testing and analysis. Many such devices provide for a sample pickup element to be fixed within the line of flow. Retractable sampling devices include hardware that is periodically inserted into the flow line and then withdrawn after the sample has been collected.
Prior U.S. Pat. No. 3,555,910, issued Jan. 19, 1971 to the instant assignee, provides a sampling apparatus for periodically withdrawing sample amounts of free flowing material from a continuous stream for testing. Such materials may be in a pressurized or non-pressurized tube, conduit or chute. The sample is obtained by extending a sample gathering apparatus into the tube or conduit capable of intercepting a portion of the moving material and then retracting the sample. The removal of the sample from the sampling device is accomplished by a controlled blast of air under pressure to move the material into an appropriate sample collecting container. This sampling apparatus is usable with free flowing granular material such as grain and the like and also with fluids.
A significant problem with prior art samplers that utilize suction techniques for withdrawing liquid samples is sampling errors caused by delays between suction shutoff instructions, relayed by the electronics, and the cessation of sampling intake. For the resultant sample to match that requested by a user, the software must make adaptive corrections to insure that the correct sample mass or weight is obtained, notwithstanding the delays occasioned by vacuum suction transfer techniques.